1. Field of Invention
The invention relates to a safety shut-off device for sections of fluid circuits that, in case of damage or the like, have to be shut off from each other on safety considerations.
2. Related Technology
Such safety shut-off devices are provided in order to shut off single sections of, for example, refrigerant or hydraulic circuits in case of damage and to prevent the fluid contained in the circuits from completely flowing out. This ensures that the outflow of fluids (which are relevant considering safety, cost-intensive and hazardous for the environment or health) from a damaged circuit is limited.
It is known in the state-of-the-art to be anxious to shut off various circuit sections, for example refrigerant circuits. The peculiar problem is the fact that the refrigerants are substances that are hazardous for the environment or, due to enrichment of refrigerants in the areas being air-conditioned, are hazardous to the persons in these areas. This is particularly relevant for refrigerant plants in motor vehicles where, in case of damage, the passengers could be confronted with the refrigerant in a very small space.
U.S. Pat. No. 5,918,475 proposes, in case of damage of vehicle air conditioning units, to dose, for example, the air exit of the air conditioning unit into the passenger compartment in order to prevent or reduce the entry of refrigerant into the passenger compartment. Following this strategy, however, does not avoid the loss of refrigerant from the system; only the entry of refrigerant into the passenger compartment will be reduced.
A particular disadvantage is that, in the case of damage, it cannot be ensured that no other leaks or connections to the passenger compartment developed, which would allow the refrigerant to flow into the passenger cell.
The solution, in the case of damage to only single parts or sections of the refrigerant plant that has been know for long and is described in the state-of-the-art. One possibility is that an externally controlled valve is closed in a de-energized condition and therefore shuts off the evaporator exit. Another possibility is to provide non-return valves in order to prevent any unintentional exit of the refrigerant due to back flowing of the refrigerant into sections affected by the damage.
According to the teachings of U.S. Pat. No. 5,983,657 it is proposed (for a vehicle air conditioning unit) to use a combination of an electromagnetic valve and anon-return valve to prevent the refrigerant from flowing out of the evaporator when the compressor is not operating. The decompression valve is used as the electromagnetic valve.
A disadvantage of the described state-of-the-art, particularly if the decompression valve is used as a shut-off valve, is that the decompression valve is limited in its true function due to the added sealing function. Further, a decompression device extended by such an additional function is more cost-intensive because of the higher complexity of the structure.
This invention is therefore aimed at the establishment of a safety shut-off device that undertakes the shut-off of sections or line loops of a fluid circuit without an expensive control.